hide
Free keywords:
-
Abstract:
Using three different techniques - X-ray photoemission (XPS), near-edge X-ray absorption spectroscopy (NEXAFS) and diffuse LEED - we have studied the adsorption and reaction of CO2 on Ni{ll0}. In agreement with previous angle-resolved photoemission (ARUPS) and vibrational electron energy loss (EELS) data both a linear, physisorbed molecule and a bent, chemisorbed species CO2δ- are found. An evaluation of the XPS line intensities shows that the stoichiometry of the chemisorbed species is 1 to 2 in carbon and oxygen. The polarisation dependence of the NEXAFS indicates that the physisorbed molecule lies with its axis parallel to the surface and that the molecular plane of the CO2δ- species is perpendicular to the surface. There is no clear preferential azimuthal orientation. This is in agreement with a diffuse LEED analysis where equal numbers of bent molecules adsorbed on atop sites and oriented along the (100) and (110) directions gave the best fit to the data.
